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He pledged to oppose and veto any attempt to infringe upon the right keep and bear arms.

“I pledge to continue to stand strong in support of the Second Amendment” and to protect Kansans’ right to keep and bear arms, Colyer said.

Earlier in the day, Kobach announced an endorsement by Gun Owners of America. In an apparent dig at the NRA, his campaign described Gun Owners of America as “the only no-compromise gun lobby organization in the nation.”

“Gun Owners of America is committed to endorsing leaders who fight back in Second Amendment battles. They know that the right of law-abiding citizens to protect their families is non-negotiable. I will never back down in defense of those rights,” Kobach said in a statement.

Immediately after the endorsements were released, the NRA’s website listed Colyer’s grade as an A, and Kobach’s grade as an A+. But a few minutes later, after the page was refreshed, Kobach’s grade was listed as an A.

Kobach’s campaign later released the NRA’s letter to Kobach, which gives Kobach an A. Another Republican candidate, Insurance Commissioner Ken Selzer, also received an A rating. Moderate Republican candidate Jim Barnett received an F rating.

In response to the NRA endorsement, the Kobach campaign pointed to a poll of Kansas State Rifle Association members that showed Kobach leading other Republican candidates, with support from more than 56 percent of members.

“It’s not even close among gun owners in Kansas. They overwhelmingly prefer Kris Kobach. The NRA’s fixation on protecting incumbents is counterproductive to protecting gun rights,” Kobach spokesperson Danedri Herbert said.

Kansas has loosened restrictions on gun rights several times over the past few years.

Lawmakers implemented concealed carry, then later removed a requirement that individuals hold permits to have a concealed weapon. And public universities and colleges can no longer prohibit weapons on campus.

The Democratic candidates for governor, who will also compete for votes in an August primary, have promised to support reversals of some of those policies. Every major Democratic candidate received an F rating from the NRA.

National Rifle Association executive vice president and CEO Wayne LaPierre said opponents of gun rights "hate individual freedoms" and want to eliminate the 2nd Amendment.